In a powered vehicle having an engine, the engine can have problems that cause extreme torque spikes. One such engine problem would be coolant released into the engine's intake thereby immediately stopping the engine. The immediate stop can cause a significant torque spike to pass through an input shaft of a transmission coupled to the engine. In some instances, the input shaft can be fractured or damaged due to the torque spike. Alternatively, in an engine and transmission system, the natural frequency of the system can cause high torque spikes. These extreme torque spikes can also cause damage to the transmission.
To reduce or prevent this damage from torque spikes, an input damper can be connected between the engine and input shaft of the transmission. During normal engine operation, a conventional input damper can “dampen” or reduce the torque spike or torsional so that a substantially constant amount of torque is transferred to the input shaft. To do so, the conventional input damper can include a plurality of springs and stops such that rotational energy received by the input damper causes rotation or angular displacement of the springs. In other words, the springs are compressed to dampen the rotational energy (i.e., input torque). However, conventional input dampers have a limited capacity at which point the plurality of springs reach the end of their respective spring travel. In this instance, the input damper becomes a solid coupling between the torque-generating mechanism and the input shaft and undampened torque spikes can affect the input shaft and transmission.
To limit the torque spikes transmitted to the input shaft, torque-limiting clutches can be employed in conjunction with the conventional input damper. Conventional torque-limiting clutches can have a wide range of capacities due to tolerance stacks. In one aspect, a conventional input damper can be designed in conjunction with a torque-limiting clutch at or near the maximum capacity of the input damper. The clutch may slip before full capacity or, alternatively, reach the full capacity at which point an extreme torque spike is fully transferred to the input shaft.
Thus, a need exists for providing a means for preventing or reducing torque spikes and other torsional impact from exceeding the capacity of the input damper.